In Criminal Case, the player acts as a detective to solve murder cases, locating relevant clues at crime scenes by clicking items in the scene. Rapid clue location is rewarded with greater scores; the player earns stars that can later be used as a type of currency for performing necessary tasks such as examining evidence and interrogating suspects. At the conclusion of every case, the player is presented with all the suspects and must arrest the one who fulfills each of the criteria gained throughout the investigation. If the decision is correct, the case is solved. To unlock the next case, however, the player is also required to complete the solved case's post-indictment chapter, enabling the player to receive reports and finally move on to the succeeding case—though this procedure does not have to be undertaken in any of thetutorialcases. There are also puzzle elements and various progression and bonus features integrated into the game.

Initially presented as a British senior apprehensive to modern technology, Rupert joins Amir and the player to DreamLife's launch party for their new virtual reality game. After taking a liking to it, Rupert gradually gets addicted to the game, even neglecting his job in order to play the game. Eventually, he becomes a suspect in the murder investigation of the game's virtual hostess, where the extent of his addiction is shown. After the investigation closes, the team finds a cure for the addicted players, and Rupert is able to stop playing the game.

A few weeks later, the team find out that Rupert's old schoolmate and lookalike, Mortimer Pickering, has been employed by DreamLife to study the meteorite they have been hiding under the dome. Rupert proposes that he take Mortimer's place under the dome, and starts studying geology, all the while trying to concoct a cure for the neurotoxin of the Demon Fish infesting the Maple Heights floodwaters.